What kind of terrier is knock knock?

Knockknock is a knock at the beginning of a joke, and it is the prologue of the oldest joke in a foreign language. "Duanzi" is an artistic term in cross talk, which refers to a paragraph or an artistic content in cross talk works. However, with the frequent use of the word "Duan Zi", its connotation has quietly changed, and people unconsciously and subjectively incorporated it into some unique connotations.

Now this word is not only the original meaning, but also the common name of vocal music programs or literary works, so with the expansion of the meaning of this word, something has appeared. Ironically, cradle art has been included in the paragraph.

"Red joke" is a kind of positive, healthy and upward information spread on computers, mobile phones and other media through the Internet. Its main forms are inspirational short sentences, philosophical proverbs, management proverbs, epigrams, sincere wishes, humorous sketches and so on.